In recent years, digital circuit technologies such as the LSI (Large Scale Integrated) circuit are used not only for computers or communication-related equipment, but also for home appliances or in-vehicle equipment.
As devices are becoming smaller, smaller parts are required. In addition, as operating frequencies have been increased as a result of increase in the operating speed of each device, the LSI mentioned above requires a large amount of current. Therefore, a part to supply the large amount of current to the LSI is needed.
A high-frequency current generated in, for example, the LSI does not stay in the vicinity of the LSI. The high-frequency current widely spreads in the mount circuit board such as a printed-circuit board, inductively couples to the signal wirings and ground wirings, and then leaks from, for example, the signal cables as an electromagnetic wave.
In mixed-signal circuits having both of an analog circuit and a digital circuit, such as a conventional analog circuit a part of which is replaced with a digital circuit, or a digital circuit having an analog input/output, one of the serious problems is electromagnetic interference from the digital circuit to the analog circuit.
In order to overcome the above problems, a ceramic capacitor 600 is used to deal with the problem of noise, however, there are problems in that changes in the characteristics, such as temperature, are drastic. A tantalum solid electrolytic capacitor 700, which is small in size but has a large capacity, is also used, however, its impedance at a high frequency is great, and noise is not reduced to a sufficient level.
To deal with the above-mentioned problems with the characteristics, a well-know composite part 800 comprises the tantalum solid electrolytic capacitor 700 and the ceramic capacitor 600, which are connected parallel to each other with a lead frame 601 interposed therebetween, and is sealed with an external resin member as shown in FIG. 12 (Patent Document 1).    Patent Document 1: Japanese Unexamined Patent Application Publication No. 9-232196.